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Chemistry Past Questions

Study and practice Chemistry past questions with answers and detailed explanations. Then test your knowledge using our interactive CBT practice platform and prepare confidently for your upcoming examinations.

123 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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123 questions

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Question 31

waec 2003

Which of the following statements about an exothermic reaction is correct?

Athe products have less heat content than reactants

Bthe system absorbs heat from the surrounding

Cthe activation energy is high

Dthe enthalpy change is positive

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Question 32

waec 2003

Sea shells contain mainly CaCO ₃. Calcium oxide can be prepared from sea shells by

Aadding dilute acid

Bheating at a high temperature

Creduction with CO

Dadding dilute NaOH_(aq)

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Question 33

waec 2003

Which of the following processes involves neutralization?

AHardening of oils

BSouring of milk

CCharring of sugar

DLiming of soil

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Question 34

waec 2003

The pH of 0.50 mol dm^-3 solutions of HCI, H₂SO₄ and CH₃COOH were measured. which of the following statements about the values obtained is correct?

Athe pH value was equal to 5 in each case

Bthe pH values of the HCI and H₂SO₄ solutions were equal

Ctheir pH values added uo to 14

Dthe pH value of the CH₃COOH was the highest.

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Question 35

waec 2003

What term is used to describe an oxide whose aqueous solution turns blue litmus red?

AStrong electrolyte

BAcid anhydride

CAmphoteric oxide

DBasic oxide

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Question 36

waec 2003

Substance Q reacts with cold water to form a solution which turns red litmus blue. Substance Q could be

Azinc

Bphosphorus

Clead

Dsodium

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Question 37

waec 2003

Which of the following solutions will give a precipitate with dilute tetraoxosulphate (V) acid? l. Lead (ll) trioxonitrate (V) solution ll. Barium chloride solution lll. Sodium chloride solution

Al only

Bll only

Cl and ll only

Dll and lll only

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Question 38

waec 2003

Which of the following salts can be prepared by reacting the metal with dilute H₂SO₄?

ACuSO₄

BMgSO₄

CBaSO₄

DPbSO₄

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Question 39

waec 2003

Bees inject an acidic substance when they sting. Which of the following chemical could be used to treat bee stings?

ACH₃COOH

BNaHCO₃

CC₂H₅OH

DH₂O₂

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Question 40

waec 2003

Which of the following acids is dibasic?

AHydrochloric acid

BTrioxosulphate (IV) acid

CDioxonitrate (lll) acid

DEthanoic acid

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Question 41

waec 2003

Which of the following quantities is the same for one mole of Br_2(l) and one mole of He_(g)?

ANumber of molecules

BNumber of atoms

CTotal mass of the particles

DVolume occupied at s.t.p

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Question 42

waec 2003

Which of the following statements about dative bonding is not correct?

Athere is sharing of electrons

Bone atom must possess a lone pair electrons

Ceach participating atom contributes one electron

Dit can be formed between molecules

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Question 43

waec 2003

An element X with electronic configuration \(1S^22S^22P^63S^2\) combines with another element Y with the configuration \(1S^2S^22P^23S^23P^5\). What is the formula of the compound formed?

AX₂Y₅

BX₂Y₃

CXY₃

DXY₂

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Question 44

waec 2003

Group O of elements are unreactive because

Atheir outmost shells contain equal number of electrons

Btheir highest occupied enegy level is full

Cthey are monatomic gases

Dthey are non-metals

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Question 45

waec 2003

The electronic configuration of an element is 1\(s^2\) 2\(s^2\) 2\(p^6\) 3\(s^2\) 3\(p^3\). Where is the element located in the periodic table?

AGroup lll, period 3

BGroup lll, period 5

CGroup V, period 3

DGroup V, period 5

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Question 46

jamb 2003

2HCI(ag) + CaCO\(_3\)(s) → CaCl\(_2\)(s) + CO\(_2\)(g) + H\(_2\)O(l). From the reaction above, which of the curves in the diagram represents the production of carbon (IV) oxide as dilute HCI is added?

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Question 47

jamb 2003

The principal constituent of natural gas is

Amethane

Bethane

Cpropane

Dbutane

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Question 48

jamb 2003

Which of the following is found in cotton

AStarch

BCellulose

CFat

DOil

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Question 49

jamb 2003

The process by which atoms are rearranged into different molecular structure in the petroleum refining process is referred to as

Acatalytic cracking

Bhydrocracking

Cpolymerization

Dreforming

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Question 50

jamb 2003

A compound contains 40.0% carbon 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180, find the molecular formula.
[H = 1, C = 12, O = 16]

ACH₂O

BC₃H₆O₃

CC₆H₁₂O₆

DC₆H₁₂O₃

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